During Hayd, women should not:
- Perform Salah, whether obligatory or Nafl prayers. The Prophet (Salla Allahu 'Alayhi Wa Sallam) said to Fatimah bint Abi Hubaysh (Radi'Allahu Anha): “When it is menstrual blood it is dark and recognizable, so when it is like that, then stop praying, and when it is otherwise, do Wudu and pray, for that is from a vein.” Women do not need to make up missed prayers. Istihadah does not carry this restriction at all; see praying during istihadah for the wudu she performs instead of leaving prayer.
- Fast, obligatory or voluntary. The Prophet (Salla Allahu 'Alayhi Wa Sallam) said: “Isn't it true that a woman can neither pray nor fast during her menses?” (al-Bukhari). Women must make up the obligatory fasts missed for her period afterward.
- Perform Tawaf around the Kaaba, whether for Umrah, Hajj, or Tawaf al-Wadaa. The Prophet (Salla Allahu 'Alayhi Wa Sallam) told Aishah: “Do everything that the pilgrims do except Tawaf until you become pure.” (Bukhari & Muslim). If her period begins once she is already on Hajj, see what if your period starts during Hajj for how the rest of the pilgrimage continues around that. Sa'i itself is not held to this same requirement; see can you perform Sa'i during your period for why it still waits alongside tawaf in practice.
- Enter or stay in a mosque, even for Eid prayers. Umm ‘Atiyyah (Radi'Allahu Anha) reported that the Prophet commanded menstruating women to stay away from the prayer-place of the Muslims. (Bukhari & Muslim). Istihadah does not carry this restriction either; see can a woman with istihadah enter the mosque for the direct evidence that she may even remain inside one.
- Touch the Mushaf without a barrier. Allah says: “None shall touch it except the purified.” [Al-Waqiah 56:79].
- Engage in sexual intercourse. Allah says: “They ask you concerning menstruation. Say: It is a harm, so keep away from women during menses and do not approach them until they are purified.” [Al-Baqarah 2:222].
It is noteworthy that these prohibitions carry mercy and ease for the woman during her menstruation.
Continuing an i'tikaf already under way is also not possible once bleeding starts, since i'tikaf is dwelling inside the mosque itself rather than a separate act. See what if your period starts during i'tikaf for what happens to the days already spent, and how the schools differ on resuming or making them up.
All of these, except the fast, lift together once ghusl is performed: see how to perform ghusl after your period ends for the full steps and what changes once it is done. Fasting is the one exception: it becomes valid again the moment the bleeding itself stops, even if ghusl is still pending when Fajr arrives.